Combined notching and jetting methods and related apparatus

ABSTRACT

An apparatus and several methods for forming one or more channels from an existing cased wellbore are disclosed. In one embodiment, the apparatus includes a notching device for forming an opening in the casing and having an integral guide shoe portion for guiding a nozzle to a position adjacent the opening to form the channel. The related method may involve lowering this apparatus into the well and then performing the notching or jetting operation, or separately lowering a notching device and a guide shoe, each carried on the end of a tubing, into the well. A guide shoe capable of positioning the nozzle close to the opening in the casing, such as one formed during the notching process, is also disclosed.

RELATED APPARATUS

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 60/179,198, filed Jan. 31, 2000 and U.S. Provisional Application Ser. No. 60/201,955, filed May 5, 2000, the disclosures of which are both incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention relates generally to the recovery of natural resources by boring in the earth and, more particularly, to the combined use of notching techniques to form one or more openings in a well casing and jetting techniques to create one or more channels from the one or more openings thus formed.

BACKGROUND OF THE INVENTION

[0003] Different devices for “slotting” or “notching” cased wellbores (or alternatively “fracturing” the surrounding strata from cased or uncased wellbores) to improve oil or natural gas production are known in the art. Examples of several common types of such devices are found in U.S. Pat. No. 4,346,761 to Skinner et al., U.S. Pat. No. 4,134,453 to Love et al., U.S. Pat. Nos. 4,050,529 and 4,047,569 to Tagirov et al., U.S. Pat. No. 3,318,395 to Messmer et. al., U.S. Pat. No. 3,145,776 to Pittman, U.S. Pat. No. 3,130,786 to Brown et al., U.S. Pat. No. 2,838,117 to Clark, Jr. et al., U.S. Pat. No. 2,758,653 to Desbrow, and U.S. Pat. No. 2,315,496 to Boynton. The disclosures of each of these patents are incorporated herein by reference.

[0004] Despite the fact that the devices described in these patents generally enhance productivity, their effectiveness is somewhat limited. The primary shortcoming is that each device relies primarily on one or more fluid jets issuing from a notching device or tool suspended in the well to provide the penetrating or eroding action to form an opening in the casing. Of course, even if one or more fluid jets are capable of penetrating through the casing, there are practical limits on the depth or distance that any fluid jet may penetrate into the strata. Consequently, the ability to reach remote pockets of oil or gas is generally limited.

[0005] To reach deeper into the strata, others have proposed the use of jetting techniques to form horizontal extensions or lateral channels from a primary wellbore. When no casing is present, it is possible to simply lower a hose or coiled tubing, possibly carrying a nozzle, through a passageway in a guide shoe or the like into engagement with the inner wall of the wellbore. A fluid under pressure is then supplied to the hose. The fluid jets out into engagement with the strata and forms the desired lateral, or horizontal channel. An early example of a device employing this technology is found in U.S. Pat. No. 2,258,001 to Chamberlain, issued Oct. 7, 1941, which is also incorporated herein by reference.

[0006] In cased wells, the application of horizontal jetting techniques is usually not so simple, since a prerequisite to forming one or more lateral channels is penetrating the casing, which is typically formed of steel or other hardened metals. The use of nozzles in conjunction with abrasive-laden fluids for penetrating the casing is possible, and has been suggested by others in the art. However, a deleterious complicating factor is that most low-cost abrasives, such as sand, tend to clog the passageways or otherwise wear the nozzles out in a short amount of time. This shortcoming increases the drilling expense and makes this arrangement unreliable for regular use.

[0007] Instead of using notching or horizontal jetting techniques to penetrate the casing, others in the past have proposed the use of mechanical devices to cut an opening in the casing to allow the hose or coiled tubing carrying the nozzle to move into direct engagement with the grout or surrounding strata. Recently, a great amount of effort has been devoted to developing the simplest, most reliable, and least expensive method of mechanically cutting through the casing. Some have proposed the use of punches that penetrate the casing, as found for example in U.S. Pat. No. 4,640,362 to Schellstede and later in U.S. Pat. No. 5,392,858 to Peters et al., both of which are incorporated herein by reference. While these devices are generally effective for their intended purpose, they suffer from being extremely complex in design and operation, as well as expensive to transport and operate. Moreover, their overall size makes them not only cumbersome, but also suitable for use only in relatively deep wells.

[0008] Another, more recent proposal is to use a conventional mill or the like to grind away at the casing to form the aperture, as described in ARCO's reexamined U.S. Pat. No. 5,435,400 to Smith, which is incorporated herein by reference. Despite the apparent simplicity of this approach, it suffers from several disadvantages in practice. The most obvious disadvantage is that the use of a mechanical cutter is extremely time consuming, since the casing is slowly cut, burnished, or ground away.

[0009] Accordingly, an alternative method of and apparatus for forming one or more lateral channels from a cased well is needed. The method and apparatus would eliminate the need for punches, ball cutters, mills, underreamers, or other types of devices that must be actuated or actively rotated at high speeds at a downhole location, and yet would be capable of forming at least one, and preferably a plurality of lateral channels from the well in a most expeditious and economical fashion, even when a casing is present. Overall, this alternative approach would result in a simpler, more cost effective, and more reliable manner of forming additional channels from a primary wellbore to enhance productivity, as compared with the above-described prior art approaches.

SUMMARY OF THE INVENTION

[0010] In accordance with a first aspect of the present invention, a method of forming one or more channels from a well having a casing is disclosed. The method comprises: notching at least one opening in at least the casing using an abrasive fluid; supplying a jetting fluid to flexible hose carrying a nozzle positioned in the opening such that the fluid issues from the nozzle against any adjacent material to form at least one first channel; and advancing the nozzle and hose into the first channel. Positioning the nozzle may include moving it through the opening and into engagement with any material surrounding the casing prior to providing the jetting fluid to the hose.

[0011] In one embodiment, the step of notching the casing includes: (1) positioning a tubing including a notching device having at least one port in the well at a first location; and (2) supplying the abrasive fluid under pressure to the notching device such that the abrasive fluid issues from the port to form the opening in at least the casing. The method may also further include the steps of positioning a guide shoe including a passageway having an outlet adjacent to the opening and positioning the nozzle in the opening by passing the nozzle into the passageway and out the outlet. The passageway may further include an inlet, in which case positioning the nozzle includes passing the nozzle through the inlet. The passageway may also be at least partially formed in a pivoting elbow for redirecting the nozzle toward the opening in the casing, in which case the method may also include pivoting the elbow from a first retracted position to a second position when the outlet is adjacent to the opening in the casing.

[0012] It is possible to carry the guide shoe on the tubing along with the notching device, in which case a stopper is provided for blocking the passageway in the guide shoe. The stopper is placed in an operative position prior to supplying an abrasive fluid to the notching device. Once the at least one (or a plurality of) openings are formed, the method may include removing the stopper from the operative position. The removing step may involve providing an ejecting flow of fluid in the annulus formed between the tubing and the casing such that the fluid flows in the outlet of the passageway to remove the stopper from the operative position. Preferably, a sufficient amount of ejecting fluid is supplied to return the stopper to the surface.

[0013] In one embodiment, the at least one port in the notching device is upstream of the outlet of the passageway in the guide shoe, and the step of positioning the outlet of the guide shoe adjacent the opening includes raising the tubing. The raising of the tubing may be for a predetermined distance. It is also possible to bias the outlet of the passageway toward the opening in a direction where the at least one lateral channel is desired such that an outwardly projecting portion of the guide shoe carrying the outlet is lodged in the opening when the tubing is raised. The outwardly projecting portion may also include a sloping nose adjacent to the outlet, such that after the at least one first channel is formed, the tubing may be raised until the sloping nose engages an upper ledge of the opening to overcome the biasing force and dislodge the guide shoe.

[0014] The method may further include the steps of withdrawing the notching device from the well after a desired number of openings are formed and positioning a tubing carrying a guide shoe into the well having a passageway for redirecting the nozzle to a position adjacent a selected opening. As noted above, the passageway may be formed in a pivoting elbow, in which case the method includes pivoting the elbow from a first retracted position to a second position to place the outlet adjacent to the selected opening. The step of positioning the notching device may include positioning the tubing in the well at a first location and supplying the abrasive fluid to form at least one opening, and then repeating the positioning of the notching device and supplying steps a plurality of times at a plurality of different locations to form a plurality of openings prior to withdrawing the notching device from the well.

[0015] The method may also include: (1) rotating the notching device as the abrasive fluid issues from the port to form a semi-annular or annular window in the casing; (2) raising and lowering the notching device as the abrasive fluid issues from the port to increase the vertical dimension of the opening formed in the casing; or (3) using the nozzle to form at least two channels extending in different directions from the at least one opening in the casing. Also, the at least one opening may be a first opening, and the method may further include notching a second opening in the casing at a different location, positioning the nozzle adjacent to the second opening, and jetting into any material adjacent the second opening to form at least one second channel.

[0016] In accordance with a second aspect of the invention, a method of forming one or more channels from a casing in a well is disclosed. The method comprises: positioning a tubing carrying a notching device having at least one port and a guide shoe having a passageway with an outlet at one or more locations in the well; positioning a stopper to the passageway; supplying an abrasive fluid under pressure to the tubing such that the abrasive fluid issues from the port to form at least one opening in at least the casing at each location where the notching device is positioned; removing the stopper; aligning the outlet of the passageway with the opening; passing a nozzle carried on a hose through the tubing, into the passageway, and out the outlet to a position adjacent the opening; and supplying a jetting fluid to the hose, the fluid issuing from the nozzle into engagement with any material adjacent the opening to form a first channel. The method may also include advancing the nozzle into the opening to form the first channel, retracting the nozzle once the first channel is formed, aligning the outlet of the passageway with an opening at a different location, and repeating the supplying and advancing steps to form a second channel.

[0017] In accordance with a third aspect of the invention, an apparatus for forming one or more channels from well having a casing is disclosed. The apparatus comprises a tubing for lowering down the well. The tubing carries a notching device including at least one port for issuing an abrasive fluid to form an opening in the casing. A nozzle carried on a hose is provided for jetting through the opening to form at least one channel in any material surrounding the casing. A guide shoe is also carried on the tubing for positioning the nozzle adjacent to the opening.

[0018] Preferably, the guide shoe is carried on the tubing downstream of the notching device and includes an inlet and an outlet connected by a passageway. The passageway redirects the nozzle out the outlet and towards the opening in the casing. A stopper is provided for initially blocking the inlet but allowing the abrasive fluid to pass through the at least one port in the notching device. Means for removing the stopper from the inlet after the opening is formed is also provided. In one embodiment, the means includes a pressurized fluid for passing through an annulus formed between the tubing and the casing, in the outlet, and through the passageway to unseat the stopper.

[0019] Also in the preferred embodiment, the port is upstream of the outlet, and the apparatus further includes means for raising the guide shoe such that the outlet of the passageway is substantially aligned with the opening in the casing. One of the tubing, the guide shoe, or the notching device may be provided with at least one centralizer for biasing the outlet toward the opening in the casing in a direction where the at least one channel is desired. In one embodiment, the outlet is formed in an outwardly projecting portion of the guide shoe and the raising means moves the tubing until the outwardly projecting portion lodges in the opening. The outwardly projecting portion of the guide shoe may further include a sloping nose adjacent to the outlet that engages an upper ledge of the opening to overcome the biasing force supplied by the centralizer and dislodge the outlet therefrom when the tubing is raised.

[0020] In accordance with a fourth aspect of the invention, an apparatus for attachment to a tubing for forming a channel from a cased well using an abrasive fluid to form at least one first opening in the casing in combination with a nozzle attached to a hose for jetting out the first opening and into the material surrounding the casing, is disclosed. The apparatus comprises a notching device including at least one port for issuing the abrasive fluid toward the casing to form the opening therein. A guide shoe is also provided adjacent to the notching device, the guide shoe including at least one passageway having an outlet for directing the nozzle toward the opening in the casing once formed.

[0021] In one embodiment, the guide shoe is positioned downstream of the notching device, and the notching device and guide shoe are integrally formed with each other. The notching device may include a plurality of ports, with the ports being either substantially vertically aligned or circumferentially disposed. Also, the passageway of the guide shoe may be provided in an elbow capable of selectively pivoting between a first retracted position and a second position such that the outlet of the passageway is adjacent to the opening in the casing. An actuator may also be provided for pivoting the elbow between the first and second positions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is an enlarged, partially cutaway, cross-sectional side-view of one embodiment of the channel forming apparatus of the present invention, illustrating in particular a stopper in the form of a ball used to seal off the inlet to the passageway of a guide shoe portion and a plurality of ports formed in a notching device upstream from the passageway for forming an opening or window in the casing, such as when the notching device is rotated;

[0023]FIG. 2 is a view similar to FIG. 1, showing the reverse circulation of fluid through the annulus between the casing and the tubing that serves to remove the stopper ball and wash away any residual abrasive;

[0024]FIG. 3 is a view similar to FIGS. 1 and 2, but showing the tubing in a raised position such that the outlet of the passageway downstream from the notching device is aligned with both the newly formed opening or window in the casing and a precut extension in the material surrounding the casing;

[0025]FIG. 4 is a view similar to FIGS. 1-3, but showing an embodiment wherein a centralizer (bow spring) serves to bias the outlet of the guide shoe portion into the opening or window such that it is lodged in place during the jetting operation; upon raising the tubing, a sloping nose on the front face of the guide shoe portion serves to dislodge it from the window;

[0026]FIGS. 5a and 5 b are different views of one possible form of a nozzle used in performing the jetting operation;

[0027]FIG. 6 is a partially cutaway side view showing one environment in which the apparatus and methods disclosed herein find significant utility;

[0028]FIG. 7 is a partially cutaway side view of a weight bar that may be used for coupling together two adjacent sections of hose or coiled tubing;

[0029]FIG. 8a is an enlarged partially cross-sectional, partially cutaway side view of a guide shoe including a pivoting elbow in a retracted position;

[0030]FIG. 8b is a view similar to FIG. 8a, with the elbow portion of the guide shoe in the operative position;

[0031]FIG. 8c is a cross-sectional view taken along line 8 c-8 c of FIG. 8a; and

[0032]FIG. 9 is a view similar to FIG. 8a, but showing an alternate embodiment wherein a notching device is positioned upstream of the guide shoe having a pivoting elbow.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Reference is now made to FIG. 1, which shows one possible embodiment of an apparatus 10 for practicing one version of an improved method of forming lateral channels from a cased well, as further described herein. In one embodiment, the apparatus 10 includes a tubing 11 carrying a notching device 12 having a guide shoe portion 13. The notching device 12 includes at least one, and most preferably a plurality of outwardly directed ports 14, openings or nozzles for expelling an abrasive fluid F_(a) forced down the tubing 11 into contact with the inner wall of the casing C. Preferably, the ports 14 are formed of or coated with abrasion resistant materials, such as tungsten carbide, as are the inner and adjacent outer surfaces of the tubing 11 to guard against splashing. As illustrated, a series or vertically aligned ports 14 may be provided in the notching device 12. Alternatively, the ports 14 may be disposed around the circumference of the notching device 12 in the same or different horizontal planes (not shown). Of course, any arrangement of ports 14 is possible as long as the desired function of expelling an abrasive fluid to erode the casing C and form an opening at the desired location is reliably achieved.

[0034] In the illustrated embodiment, an internal passageway 16 is provided in the guide shoe portion 13 of the notching device 12 just downstream of the ports 14. The passageway 16 may include a tapered, frusto-conical inlet 18, which as described further below, is adapted for receiving and guiding a nozzle attached to the end of a flexible hose, coiled tubing or the like (the two are considered equivalents for purposes of the present disclosure), into the passageway (see phantom representation of hose in FIG. 3 and the full line representation in FIG. 4). The passageway 16 is generally J-shaped in cross-section and also includes an outlet 20 positioned adjacent to the inner surface of the well casing C when the notching device 12 is in the operative position. Preferably, the passageway 12 includes exhaust ports P for allowing any debris entering through the outlet 20 to escape. FIG. 1 shows the ports P formed in the lower surface of the passageway 16, but it should be appreciated that their location could vary depending on the particular arrangement used, as long as the corresponding function is retained.

[0035] In operation, the tubing 11 is lowered down the well to the location where one or more lateral channels are desired. A stopper, preferably in the form of a ball 22, is then positioned in the tubing 11 to substantially seal the inlet 18 to the internal passageway 16, but not the port 14, which remains in fluid communication with the tubing 11 (see FIG. 1). This stopper ball 22 may be formed of metal, such as steel, or alternatively resin, polymer, composites thereof, or any other durable material. Although a ball 22 is described as the stopper in this preferred embodiment, it should be appreciated that any type of stopper or plunger that functions to substantially prevent the abrasive fluid F_(a) from flowing in the inlet 18, but not the port 14, may be employed. Also, it should be appreciated that the stopper ball 22 or other blocking device employed may be placed in the inlet 18 prior to lowering the tubing 11 down the well. Alternatively, the ball 22 may be dropped from the surface once the tubing 11 is in place in the well. In the latter case, an extra precaution may involve “rabitting” the tubing 11 during assembly at the surface. This involves passing a steel cylinder or the like having an outer diameter that is slightly less than the inner diameter of the tubing 11 through each section thereof. This process ensures that any burrs or other obstructions to the free passage of objects such as balls, hoses, nozzles, or the like are removed.

[0036] Once the ball 22 is in position and the tubing 11 is downhole, the abrasive fluid F_(a) such as a mixture of sand and water, is pumped under pressure or otherwise forced down the tubing 11. While the mixture of abrasive to fluid may vary depending on the particular operation or type of abrasive, for sand, the ratio may be approximately between 0.5 to 2 pounds of sand for each gallon of water, and most preferably about one pound. As is known in the art, the sand and water is mixed in a hopper (not shown) or the like and pumped into the tubing 11 using a standard oil field pump at a pressure of approximately 500-2000 psi at between 75 to 100 barrels per minute of flow. Of course, the pressure may vary depending on the particular type of abrasive fluid used, the casing thickness, the depth of the well, or the like. Different types of abrasives and fluid additives may also be included, depending on the particular application.

[0037] Since the stopper ball 22 prevents the abrasive fluid F_(a) from flowing into the passageway 16, it instead is directed toward and issues from the ports 14 in the form of one or more radial jets (see action arrows labeled A in FIG. 1). These jets make contact with the inner wall of the casing C and, over time, erode it to form an opening. In the most preferred embodiment, the entire tubing 11 is rotated at the surface during the jetting operation (see the arcuate action arrow E at the top of FIG. 1). This causes the fluid jets issuing from the ports 14 to cut an opening in the casing C in the form of a window W, thus exposing the grout G or cement normally present (or a void, or even the surrounding strata S or formation in some cases). Depending on the degree to which the tubing 11 is rotated, the window W formed by the jets may encompass all or part of a 360° circle (i.e., in annular or semi-annular form, see the dashed line outline of the casing adjacent to the side of the notching device 12 opposite the ports in FIGS. 1-3).

[0038] Usually, the notching operation proceeds for a known period of time to ensure that the adjacent casing C is fully penetrated and the opening or window W thus formed. Of course, if the casing C is penetrated before this time, the abrasive jets form a precut extension 24 a certain distance D₁ in any surrounding material, such as the grout or cement envelope used to hold the casing C in place (note that extension 24 is shown on both sides of the well in FIGS. 1-3 for purposes of illustration only; see FIG. 4 for a depiction of an extension 24 formed along only one side of the well). This distance D₁ may be about 3-5 inches from the inner wall of the casing C, but could of course vary depending on the type and concentration of abrasive used, the pressures with which the abrasive fluid F_(a) is supplied, the depth of the tubing 11 in the well, and the overall duration of the notching process. As should be appreciated, any grout removed by the jets, as well as the abrasive fluid F_(a) and any eroded portion of the casing C, simply falls into the well, and may even circulate back to the surface, depending on the duration of the notching operation, the type of formation, and the depth of the well.

[0039] Once the opening or window W is formed, the tubing 11 may be raised or lowered as desired and the operation repeated to form openings at other locations in the well casing C. After the desired number of openings are formed, which may of course be only one, an “ejecting” fluid, such as fresh water F_(w), is pumped down the annular space, or annulus 26 as it is known in the art, formed between the tubing 11/notching device 12 and the casing C. The ejecting fluid F_(w) flows down the annulus 26 and into the well until it eventually reaches the distal end of the notching device 12, at which point it flows into the outlet 20, through the passageway 16, and into engagement with the stopper ball 22 resting or seated in the inlet 18 (see action arrows B in FIG. 2). This “reverse” circulation process removes the stopper ball 22 from the inlet 18 to the passageway 16 and preferably returns it to the surface for recovery. Additionally, the circulation of fresh fluid F_(w) through the passageway 16 and tubing 11 serves to clean any residual abrasive from these and other downhole locations, thereby ensuring that structures may freely pass into the inlet 18 during later jetting.

[0040] Of course, with the stopper ball 22 removed from the tubing 11, the inlet 18 to the passageway 16 is exposed, as shown in FIG. 3. Since the ports 14 in this most preferred embodiment are located upstream of the outlet 20, and in the case where only a single opening is formed before the ball 22 is removed, it should be appreciated that raising the tubing 11 is necessary before performing the jetting operation to ensure that the outlet 20 of the passageway 16 is aligned with the opening or window W thus formed. Raising or lowering the notching device 12 is completed either by a lifting device, such as a hoist, at the surface or other similar device, as known in the art, or possibly by a downhole device for moving the notching device 12 relative to the tubing 11 (not shown). As should be appreciated, the distance D₂ that the tubing 11 is raised may be preselected based on the known distance from the ports 14 to the outlet 20 (see FIG. 2).

[0041] Once the outlet 20 is aligned with the window W, a hose 30 or coiled tubing carrying a nozzle 32 is lowered down the well, through the passageway 16 in the guide shoe portion 13 of the notching device 12, out the outlet 20, and into engagement with the remaining grout G or exposed strata S, as the case may be (see dashed lined outline in FIG. 3). Jetting fluid, such as ultra-pure water F_(u), under pressure is then supplied to the hose 30 or coiled tubing. The fluid issues from the nozzle 32 in the form of at least one, and preferably a plurality of jets J. These jet(s) erode a channel H in the strata (see FIGS. 3 and 4). Depending on the fluid, pressures and nozzle type employed, as well as the shape of the passageway 16, the channel H thus formed may extend in a substantially horizontal direction, or may extend in several different directions.

[0042] Once a first channel is formed to a desired length, the nozzle 32 is retracted by raising the hose 30 or coiled tubing at the surface. By then rotating the tubing 11 and repeating the process, additional channels may be formed from a single opening or window W at the same level, or in one of a number of spaced openings or windows already formed in the casing C, if present (not shown). For example, and as briefly noted above, it is also possible to use the notching technique described above to form openings in the casing C at a number of different locations in the well prior to removing the stopper or ball 22, and then once the ball is removed, using the jetting technique described above in each of the openings by simply raising or lowering the tubing 11 carrying the notching device 12 to the desired depth where a selected opening is formed.

[0043] A particularly preferred embodiment of the invention that is useful where at least a semi-annular window W is formed in the casing C is shown in FIG. 4. In this embodiment, at least one external centralizer, such as a bow spring 40 is carried on the notching device 12 (which could also be located on the tubing 11, if desired). This spring 40 serves to bias the outlet 20 of the passageway 16 in a first direction towards the inner wall of the casing C. Thus, upon raising the tubing 11 to align the outlet 20 of the passageway 16 with the newly formed window W, the biasing force causes an outwardly directed portion of the notching device 12 adjacent the outlet 20 to move into and become lodged in this window W (see action arrow K in FIG. 4). This lodgement ensures the operator at the surface that the tubing 11 is properly in place and that the jetting operation may commence to form the channel H at the desired location. Also, it keeps the tubing 11 stable during the jetting operation. As should also be appreciated, it is generally unnecessary in this most preferred embodiment to rely on any precise predetermined distance for raising the casing C, since it automatically lodges in the opening or window W upon being raised.

[0044] To assist in dislodging the tubing 11 once the desired number of channels are formed from a particular opening or window W, a tapered or sloping outwardly projecting nose 42 is provided just above the outlet 20 in this embodiment. Thus, when the tubing 11 is raised, the contact between this nose 42 and the upper ledge of the casing C at the top of the window W or other opening is forced in a direction that overcomes the biasing force supplied by the centralizer/bow spring 40. The tubing 11 may then be freely raised to another location where a lateral channel is desired, or removed from the well entirely.

[0045] As should be appreciated, instead of a notching device 12 with an integral guide shoe portion 13, the one or more ports 14 and the internal passageway 16 may be integrally formed in different sections of tubing 11 that are coupled together (not shown). Also, as described further below, the notching 12 device and guide shoe 13 may be formed as separate components that are simply attached to a lower section of tubing 11, such as by a threaded or welded connection. In this arrangement, the portion containing the port 14 is usually referred to as the “notching” device or tool, and the portion containing the internal passageway is referred to as the “guide shoe” (see, e.g., FIG. 9). In any case, the tubing 11 is preferably formed of a number of segments that are threaded together, thus permitting easy assembly, adjustment, or disassembly in the field, as necessary for a particular operation.

[0046] An example of a particularly preferred form of a nozzle 32 for performing the jetting operation described above is shown in FIGS. 5a and 5 b. This nozzle 50 includes a housing 51 having a recess R for capturing a free floating spinner element 52. The spinner element 52 includes at least one transverse channel, and preferably a pair of transverse channels 54, 55 for supplying fluid to an inner cavity D. In the preferred embodiment, these transverse channels 54, 55 are orthogonal to each other. Fluid F is supplied to these channels 54, 55 by at least one axial channel, and preferably a plurality of axial channels in fluid communication with recess R. Two of such axial channels 56 a, 56 b are shown in the cross-sectional view of FIG. 5a as extending along the sides of the nozzle housing 51. As more clearly shown in the transverse cross-sectional view of FIG. 5b, the preferred embodiment includes six such channels 56 a-f, but the use of more or fewer is of course possible.

[0047] As should be appreciated, the fluid issuing from these channels 56 a-f fills the inner recess R to provide a fluid bearing for the spinner element 52. At least one fluid outlet, and preferably two such outlets 61 a, 61 b are formed in the forward end of the spinner element 52 and are angled slightly outwardly relative to the horizontal plane. In addition to providing a fluid bearing for the spinner element 52, the fluid exiting the axial chambers 56 a-f enters the transverse channels 54, 55, enters recess R, and issues through the outlets 61 a, 61 b in dual streams F₁ and F₂. Since these fluid streams F₁, F₂ exit the outlets 61 a, 61 b at an angle, and all other motion is initially prevented by the coaction of the fluid streams exiting the axial chambers 56 a-f and the fluid bearing, a slight tendency to rotate is imparted to the spinner element 52. Once initiated, this rotational motion is then further enhanced by the fluid exiting the channels 56 a-f not aligned with the transverse channels 54, 55 as the spinner element 52 rotates. Specifically, the fluid exiting the channels 56 a-f imparts tangential forces against the spinner element 52 that increase its angular velocity. The turbulence created by the multiple directions of fluid flow in the fluid bearing layer also assists in rotating the spinner element 52. It has been found that fluid under approximately 5,000 psi or greater causes the spinner element 52 to rotate at an angular velocity of about 50,000 rpm and issue dual rotating fluid jet streams F₁, F₂ through the outlets 61 a, 61 b to erode the strata. Of course, lessening the pressure reduces the angular velocity, such that the spinner element 52 may rotate at anywhere from between 5-50,000 rpm, or higher.

[0048] A cap 63 is also attached to a removable insert 62 threaded to the forward end of the housing 51. This cap 63 serves to both protect the outlets 61 a, 61 b and ensure that the fluid streams F₁, F₂ exiting therefrom are properly directed. In the preferred embodiment, the insert 62 also includes a shoulder 64 that ensures that the spinner element 52 remains captured in the recess R. Backjetting function for creating rearwardly directed fluid streams F₃ and F₄ may also be provided by rearwardly angled outlets 65, 66 formed adjacent to the inlet 68 for the hose 30. Of course, these streams F₃ and F₄ serve to increase the diameter of the channel formed by the nozzle 50. A similar type of nozzle suitable for use in completing the horizontal jetting operation as described above is manufactured by Jetstream of Houston, Inc. (Houston, Tex.) and sold under the trademark DRIL-JET.

[0049] The hose or coiled tubing 30 may be of any known type. One possible example is the segmented coiled tubing distributed by the Parker Company and sold under the POLYFLEX trademark. As shown in FIG. 6, this hose or coiled tubing 30 may be carried on a reel L or spindle at the surface. A tank N may also be provided for holding the jetting fluid, and may either be stationary as illustrated or truck mounted (not shown). The hoist or other lifting device for raising and lowering the tubing 11 is not shown in FIG. 6, but would normally be positioned adjacent to the wellhead.

[0050] If necessary to prevent leaks, high pressure couplings in the form of a tapered mating male and frusto-conical female fittings (not shown) on the corresponding end of each section of hose or coiled tubing may be held together by a correspondingly threaded coupler (not shown). A narrow gauge tubing or specialized fitting may also be necessary to connect the nozzle 32 or 50 to the segmented hose 30 or coiled tubing, since the inlet is usually of a lesser gauge.

[0051] At increased depths, it may also be necessary or desirable to weight the hose 30 or coiled tubing to ensure that the nozzle 32 or 50 is directed through the opening in the casing C with the requisite degree of force to form the channel H in the desired manner. As shown in FIG. 7, this weighting may be accomplished through the use of one or more weight bars 70 for placement between adjacent sections of the hose 30 a, 30 b or coiled tubing. Specifically, each weight bar 70 includes a threaded female receiver 72 for receiving the male fitting MF on the end of a first section of hose 30 a and a threaded male coupler 74 for insertion in the female receiver FR of the second section 30 b. A center passageway 76 permits fluid to flow between the receiver 72 and the coupler 74. Wrench flats 78 may also be provided on the external surface of the weight bar 70. As should be appreciated, the flats 78 facilitate the placement of a wrench or other tool (not shown) that may be used during the installation of the weight bar 70. Preferably, the weight bar 70 is formed of a relatively heavy, durable material, such as steel. The length, diameter, shape, and size of the weight bar 70 may vary depending on the particular application. Also, it is of course possible to use multiple weight bars on a single hose, either in series or spaced apart. Of course, it should be appreciated that any weight bar(s) present are positioned sufficiently far upstream from the nozzle 32 or 50 such that no interference is created with the passage of the downstream hose 30 through the passageway 16 and into the opening in the casing C to form a channel H having the desired length.

[0052] In another embodiment of the invention, a conventional notching device of the type described in one or more of the above-referenced patents incorporated herein by reference may be used to form one or more openings in the casing C at the same or different levels, as described above. The notching device used to form the opening(s) could also resemble notching device 12, but without the guide shoe portion 13, or could simply be a capped off section of tubing having a plurality of openings formed therein to create ports 14 (see the tubing 11 upstream of the guide shoe in FIG. 9). Once the opening or openings are formed at one or more locations, as desired the notching device is retracted or otherwise recovered from the well.

[0053] To form the channel, a guide shoe is then separately lowered down the well on a tubing to a position where an opening has previously been formed by the particular notching device or tool. The guide shoe used may simply resemble the bottom portion of the notching device 12 of FIG. 1, such that it includes a curved internal passageway 16 having an inlet 18 for receiving a nozzle 32 or 50 carried on a hose 30 or coiled tubing lowered from the surface and an outlet 20 for directing the nozzle to a position adjacent to the selected opening in the casing C. Like notching device 12, this type of guide shoe may be simply carried on the end of the tubing string.

[0054] An alternate type of guide shoe 80 is shown in FIGS. 8a-8 c. The guide shoe 80 is adapted to improve the ability of a jet nozzle or other drilling implement or device to reach the strata S, especially when an opening is formed in the casing C using the notching technique described above. In the preferred embodiment, the guide shoe 80 is an assembly carrying a pivoting elbow 82, as shown in FIGS. 8a and 8 b. In the most preferred embodiment, the elbow 82 includes an approximately 90° bend and is provided with an outlet 83 and an inlet 84 that corresponds to the outlet of a substantially vertical passageway 81 formed in the guide shoe 80. A pair of pivot pins 85 a, 85 b (only pin 85 a is shown in FIGS. 3a and 3 b) or shoulder bolts projecting inwardly from a hollow underside portion of the body of the guide shoe 80 are attached adjacent to the elbow 82 adjacent to the inlet 84. As should be appreciated, this manner of attachment allows the elbow 82 to pivot relative to the guide shoe 80.

[0055] To pivot the elbow 82 between a first, retracted position (FIG. 8a) and a second, operative position (FIG. 8b), an actuator 86 is also provided. In the illustrated embodiment, the actuator 86 is in the form of a pressure-activated cylinder 88 having a plunger 90. The free end or extension side of the plunger 90 extending outside of the cylinder 88 is attached to the elbow 82, such as between a pair of opposed tabs 92 (only one shown in FIGS. 8a and 8 b). Preferably, the cylinder 88 is hydraulically or pneumatically actuated by pressurized fluid supplied from a source (preferably at the surface) to a downhole supply line 94. Alternatively, an electric motor coupled to a linear actuator or other type of motive device may be employed to provide the force necessary to pivot the elbow 82 between the first and second positions.

[0056] Yet another alternative actuator 86 is a self-contained cylinder (not shown) filled with a gaseous substance (nitrogen, for example). Such a cylinder provides a constant biasing force against the elbow 82 to pivot the outlet toward the wall of the casing C and into the opening once reached. As should be appreciated, this advantageously avoids the need for a supply line 94. The force supplied by the cylinder would be such that it can be overcome when the elbow 82 engages the roof of the cavernous extension area 24 possibly formed during the notching process (which is shown as being slightly oversized in FIGS. 8a and 8 b for purposes of illustration).

[0057] Still another alternative is to use a passive element, such as a biasing means or spring, to constantly bias the elbow 82 toward the operative position shown in FIG. 8b. The constant biasing force would be resisted as long as the portion of the elbow 82 adjacent to the outlet 83 remains in contact with the wall of the casing C, but would cause the elbow 82 to automatically move into the window W or opening once it is reached. Retraction would be achieved by raising the elbow 82 such that it engages the roof of the cavernous extension area 24 and compresses the spring or other biasing means.

[0058] In any case, the pivoting of the elbow 82 advantageously allows the outlet 83 to be placed in very close proximity to the location where a channel is desired, especially when the opening in the casing C is formed using the notching process described above such that a window W is created. More specifically, as the tubing 11 is lowered down the well, the elbow 82 is held in the first, retracted position. As perhaps best shown in FIG. 8a, the portion of the elbow 82 adjacent the outlet 83 is preferably angled or sloped such that it corresponds in geometry to the substantially vertical sidewall of the well in the retracted position.

[0059] When the opening, such as window W, is reached, the tubing 11 is oriented such that the outlet 83 of the elbow 82 is redirected to point in the desired direction for a horizontal or lateral channel from the opening, if not already in that position. In the case of the non-self actuating actuator 86 shown in FIGS. 8a and 8 b, the cylinder 88 is then retracted, such as by removing the pressurized supply of a fluid or gas to the supply line 94. As a result of this retraction, the elbow 82 pivots to move the outlet 83 in close proximity to the strata S, grout G or other material exposed during notching, and through which the nozzle 32 or 50 penetrates to form a lateral channel H (or instead of retracting the cylinder 88 by removing the pressure, the elbow 32 is automatically extended or actuated in the self-actuating embodiment). Despite the angle provided in the elbow 82, the outlet 83 is placed in the opening and preferably in very close proximity to the strata S, grout G or other material exposed during the notching process. In one embodiment, the retraction of the plunger 90 moves the elbow 82 outwardly about 6-12 inches and through a range of approximately 20° to 30°, and more specifically about 25-27° relative to the vertical axis. Of course, greater or lesser ranges of motion are possible depending on, for example, the diameter of the well, the size of the elbow 82, the attachment point of the plunger 90, the distance or stroke through which the plunger 90 moves upon actuation or retraction, or the size of the opening, and other factors. By raising or lowering the tubing 11 with the elbow 82 in the operative position, the engagement between the upper and lower ledges of the opening or window W also provide the operator with assurances that the elbow is at the desired location.

[0060] Once the outlet 83 is positioned in the opening or window W, the hose 30 or coiled tubing is then passed through the elbow 82. This is done until the nozzle 32 or 50 exits the outlet 83 and is positioned adjacent to the strata S, grout G or other material. Pressurized jetting fluid, such as water or the like, is then supplied such that the desired lateral channel is formed.

[0061] It should also be appreciated that, while several possible embodiments of the apparatus and a related method are described above, it is also possible to make obvious modifications without departing from the basic principles of the inventions disclosed herein. For instance, in the first embodiment shown in FIGS. 1-4, the port 14 could take the form of a second passageway (not shown) adjacent to or even parallel to the passageway 16 adapted for receiving the stopper ball 22. In this embodiment, the stopper ball 22 could be specially sized to fit only in the passageway 16 for receiving the nozzle 32, thus leaving the opposite passageway open for receiving the abrasive fluids pumped down the casing during the “notching” operation. Also, the guide shoe 80 of FIGS. 8a-c could be positioned on a tubing 11 carrying an upstream notching device of any type known in the art, including tubing 11 (see FIG. 9). In that case, the initial blocking of the passageway in the guide shoe 80 could be accomplished using a stopper, such as a ball 22 or the like, as described above in detail. Also, instead of or in addition to sand, the abrasive fluid may comprise an acid or other caustic chemical agent, as permitted under any extant environmental regulations. As should be appreciated, other modifications are also possible while keeping with the spirit of the various inventions disclosed herein.

[0062] The foregoing description of the various embodiments of the apparatus and method of the present invention is presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. This description provides the best illustration of the basic principles of the apparatus and method and its practical application to thereby enable one of ordinary skill in the art to practice the invention in various embodiments and with various modifications, as suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. 

1. A method of forming one or more channels from a well having a casing, comprising: notching at least one opening in at least the casing using an abrasive fluid; supplying a jetting fluid to a flexible hose carrying a nozzle positioned adjacent to the opening, said fluid issuing from said nozzle against any adjacent material to form at least one first channel; advancing the nozzle and hose into the first channel.
 2. The method according to claim 1 , wherein the step of notching the casing includes: positioning a tubing including a notching device having at least one port in the well at a first location; supplying the abrasive fluid under pressure to the notching device, the abrasive fluid issuing from the port to form the opening in at least the casing.
 3. The method according to claim 2 , further including the steps of: positioning a guide shoe including a passageway having an outlet adjacent to the opening, and positioning the nozzle adjacent to the opening by passing the nozzle into the passageway and out the outlet.
 4. The method according to claim 3 , wherein the passageway further includes an inlet and positioning the nozzle includes passing the nozzle through the inlet.
 5. The method according to claim 3 , wherein at least a portion of the passageway is formed in a pivoting elbow for redirecting the nozzle toward the opening in the casing, and the method includes pivoting the elbow from a first retracted position to a second position when the outlet is adjacent to the opening in the casing.
 6. The method according to claim 3 , wherein the guide shoe is carried on the tubing along with the notching device, a stopper is provided for blocking the passageway in the guide shoe, and the method further includes placing the stopper in an operative position prior to supplying an abrasive fluid to the notching device.
 7. The method according to claim 6 , further including removing the stopper from the operative position after the opening in the casing is formed.
 8. The method according to claim 7 , wherein the tubing and the casing together define an annulus and removing the stopper from the operative position comprises providing an ejecting flow of fluid in the annulus such that the fluid flows in the outlet of the passageway to remove the stopper from the operative position.
 9. The method according to claim 8 , further including supplying a sufficient amount of ejecting fluid to return the stopper to the surface.
 10. The method according to claim 1 , further including moving the nozzle through the opening and into engagement with any material surrounding the casing prior to supplying the jetting fluid to the hose.
 11. The method according to claim 3 , wherein said at least one port in the notching device is upstream of the outlet of the passageway in the guide shoe, and said step of positioning the outlet of the guide shoe adjacent the opening includes raising the tubing.
 12. The method according to claim 11 , wherein the raising of the tubing is for a predetermined distance.
 13. The method according to claim 11 , further including biasing the outlet of the passageway toward the opening in a direction where the at least one channel is desired.
 14. The method according to claim 13 , wherein the outlet of the passageway is formed in an outwardly projecting portion of the guide shoe, and the raising of the tubing is completed until the outwardly projecting portion is lodged in the opening as a result of the biasing step.
 15. The method according to claim 14 , wherein the outwardly projecting portion includes a sloping nose adjacent to the outlet of the passageway in the guide shoe, and after at least one first channel is formed, the method further includes raising the tubing until the sloping nose engages an upper ledge of said opening to dislodge the guide shoe from the opening.
 16. The method according to claim 2 , wherein the method further includes: withdrawing the notching device from the well after a desired number of openings are formed; and positioning a tubing carrying a guide shoe into the well having a passageway for redirecting the nozzle to a position adjacent a selected opening.
 17. The method according to claim 16 , wherein the passageway is formed in a pivoting elbow, and the method includes pivoting the elbow from a first retracted position to a second position to place the outlet adjacent to the selected opening.
 18. The method according to claim 16 , wherein the step of positioning the notching device includes positioning the tubing in the well at a first location and supplying the abrasive fluid to form the at least one opening, and then repeating the positioning of the notching device and supplying steps a plurality of times at a plurality of different locations to form a plurality of openings prior to withdrawing the notching device from the well.
 19. The method according to claim 2 , further including rotating the notching device as the abrasive fluid issues from the port to form a semi-annular or annular window in the casing.
 20. The method according to claim 2 , further including raising and lowering the notching device as the abrasive fluid issues from the port to increase the vertical dimension of the opening formed in the casing.
 21. The method according to claim 1 , further including using the nozzle to form at least two channels extending in different directions from the at least one opening in the casing.
 22. The method according to claim 1 , wherein the at least one opening is a first opening, and further including notching a second opening in the casing at a different location, positioning the nozzle adjacent to the second opening, and jetting into any material adjacent the second opening to form at least one second channel.
 23. A method of forming one or more channels from a well having a casing, comprising: positioning a tubing carrying a notching device having at least one port and a guide shoe having a passageway with an outlet at one or more locations in the well; positioning a stopper in the passageway; supplying an abrasive fluid under pressure to the tubing, said abrasive fluid issuing from the port in the notching device to form at least one opening in at least the casing at each location where the notching device is positioned; removing the stopper from the passageway; aligning the outlet of the passageway with the opening; passing a nozzle carried on a hose into the passageway to a position adjacent the opening; and supplying a jetting fluid to said hose, said fluid issuing from the nozzle into engagement with any material adjacent the opening to form a first channel.
 24. The method according to claim 23 , further including advancing the nozzle to form the first channel, retracting the nozzle once the first channel is formed, aligning the outlet of the passageway with an opening at a different location, and repeating the supplying and advancing steps to form a second channel.
 25. An apparatus for forming one or more channels from a well having a casing, comprising: a tubing for lowering down the well; a notching device carried on the tubing, said notching device including at least one port for issuing an abrasive fluid to form an opening in the casing; a nozzle carried on a hose for jetting through the opening to form at least one channel in any material surrounding the casing; a guide shoe carried on the tubing for receiving and positioning the nozzle adjacent to the opening.
 26. The apparatus according to claim 25 , wherein the guide shoe is carried on said tubing downstream of said notching device and includes an inlet and an outlet connected by a passageway, wherein said passageway redirects the nozzle out the outlet and towards the opening in the casing.
 27. The apparatus according to claim 26 , further including a stopper for initially blocking the inlet but allowing the abrasive fluid to pass through the at least one port in the notching device.
 28. The apparatus according to claim 27 , further including means for removing the stopper from the inlet after the opening is formed.
 29. The apparatus according to claim 28 , wherein an annulus is defined between the tubing and the casing, and the means for removing the stopper from the inlet comprises a fluid for passing through the annulus, in the outlet, and through the passageway to unseat the stopper from the inlet.
 30. The apparatus according to claim 26 , wherein said port is upstream of the outlet, and said apparatus further includes a lifter for raising said guide shoe such that the outlet of said passageway is substantially aligned with the opening in the casing.
 31. The apparatus according to claim 30 , wherein said tubing is provided with at least one centralizer for biasing said outlet toward said opening in said casing in a direction where the at least one channel is desired.
 32. The apparatus according to claim 3 1, wherein the outlet is formed in an outwardly projecting portion of the guide shoe and said lifter raises said tubing until said outwardly projecting portion lodges in said opening.
 33. The apparatus according to claim 32 , wherein the outwardly projecting portion of the guide shoe includes a sloping nose adjacent to said outlet that engages an upper ledge of said opening to overcome the biasing force supplied by the centralizer and dislodge the outlet therefrom when the tubing is raised.
 34. An apparatus for attachment to a tubing for forming a channel from a cased well by using an abrasive fluid to form at least one first opening in the casing in combination with a nozzle attached to a hose for jetting out the first opening and into the material surrounding the casing, comprising: a notching device including at least one port for issuing the abrasive fluid toward the casing to form the opening therein; a guide shoe adjacent to said notching device, said guide shoe including at least one passageway having an outlet for directing the nozzle toward the opening in the casing once formed.
 35. The apparatus according to claim 34 , wherein said guide shoe is positioned downstream of said notching device.
 36. The apparatus according to claim 34 , wherein said notching device and said guide shoe are integrally formed with each other.
 37. The apparatus according to claim 34 , wherein said notching device includes a plurality of ports, and said ports are either substantially vertically aligned or circumferentially disposed.
 38. The apparatus according to claim 34 , wherein the passageway of the guide shoe is provided in an elbow capable of pivoting between a first retracted position and a second position such that the outlet of the passageway is adjacent to the opening in the casing.
 39. The apparatus according to claim 38 , further including an actuator for pivoting the elbow between the first and second positions. 